Hollow carbon spheres are known. For example, Xiong et al.1 have reported hollow carbon spheres having diameters between 400 to 600 nanometers made from CCl4 at temperatures between 190 and 230° C., Zhang et al.2 have reported hollow carbon spheres with a nominal diameter of 400 nanometers and made using metal zinc powder and ethanol, Su et al.3 have reported hollow carbon spheres made by coating silica spheres with carbon, and Win et al.4 have reported hollow carbon spheres with diameters between 300 nanometers and 1 micron.
Regarding hollow carbon spheres having diameters of less than 200 nanometers, U.S. Pat. No. 7,156,958 discloses a method for producing hollow carbon nanocapsules with a diameter between 3 to 60 nanometers and U.S. Patent Application Publication Nos. 2005/0079354 and 2007/0220873 disclose hollow carbon spheres with diameters less than 20 nanometers. However, these references do not disclose the size of an inner core or cavity within the hollow carbon structures. In contrast, U.S. Patent Application Publication No. 2007/0080054 does disclose an inner cavity of 5 nanometers within hollow carbon nanoparticles with a diameter of 20 nanometers and Phillips et al.5,6 reported producing hollow graphite particles as small as 30 nm in diameter.
As such, hollow carbon spheres having diameters of less than 200 nanometers have been disclosed, however hollow carbon spheres within this size range with a relatively large inner free volume have not. Therefore, a hollow carbon sphere having a diameter of less than 200 nanometers with a relatively large inner free volume would be desirable.